An electric circuit for starting a casting machine having an endless mold

ABSTRACT

An electric circuit is disclosed according to which two insulated wires are clamped in a joint between two adjacent halfmolds of a mold track. The conductive tips of the wires project into the mold for being short-circuited by the front line of the stream of poured-in melted metal. A signalling device is activated by the short-circuit to signal the instant for starting the movement of the mold tracks of the machine.

United States Patent [191 Gyiingyiis [111 3,744,545 [451 July 10, 1973 1 ELECTRIC CIRCUIT FOR STARTING A CASTING MACHINE HAVING AN ENDLESS MOLD [75] Inventor: Ivan Gyiingyiis, Montana,

Switzerland [73] Assignee: Prolizenz A.G., Chur, Switzerland [22] Filed: May 5, 1971 [21] Appl. No.: 140,394

[30] Foreign Application Priority Data May 8, 1970 Switzerland 6844/70 [52] US. Cl. 164/4, 164/87 [51] Int. Cl 822d 17/32 [58] Field of Search 164/87, 150, 154, 164/279, 274, 4

[5 6] References 'Cited I UNITED STATES PATENTS 1,139,888 5/1915 Mellen 164/156 7/1951 Giesler 164/156 11/1966 Jendraszkiewicz et al. 164/ 154 FOREIGN PATENTS OR APPLICATIONS 1,105,568 4/1961 Germany 164/281 Primary Examiner-R. Spencer Annear Attorney-Ernest F. Marmorek [57] ABSTRACT An electric circuit is disclosed according to which two insulated wires are clamped in a joint between two adjacent half-molds of a mold track. The conductive tips of the wires project into the mold for being shortcircuited by the front line of the stream of poured-in melted metal. A signalling device is activated by the short-circuit to signal the instant for starting the movement of the mold tracks of the machine.

2 Claims, 3 Drawing Figures PATENIEpJuLmma 3744545 I v sum 1 or 2 PAIENTEDJUL 110E475 v i 35744.54?

ssmanrz Fig 2 RIOR ART AN' 'ELECTRIC CIRCUIT FOR STARTING A CASTING MACIIINE HAVING AN ENDLESS MOLD BACKGROUND OF THE INVENTION This invention relates generally to casting of metal strips and, more specifically, to means for starting a casting machine of the type having two opposed endless, caterpillar-type tracks of half-molds for casting non-ferrous metals, especially aluminum and aluminum alloys. At the pour-in site, the opposed half-molds are put together'and move in this united condition across a predetermined distance. In the limits of this distance, the half-molds from the upper and lower tracks are thus composed to form the actual operative mold which, at the discharging end, is separated into individual halfmolds again and after a short period of time the halfmolds are reunited at the site of the metal pouring.

A machine of this type is described, for example, in the Swiss Pat. No. 475,811; according to this patent,

. the circulating half-molds are connected with guiding and driving members through supporting and fastening elements having a reduced total thermal conductivity. The machine, therefore, enables casting of metal strips of a considerable width, for instance 20mm thick aluminurn strips having a width of 1,500 mm and more.

For vertical downward casting in the above described prior art machine, a special metal feeding device is employed, which is also described in the patent literature, for example in the Swiss Pat. No. 461,716. It is also possible to cast downwardly at an oblique angle or even horizontally. For this purpose, the machine can be inclined at an angle between 45, preferably between and 1 downward from a horizontal line in the direction of casting. Reference is had to my applications Ser. No. 108,529 filed Jan. 21, 1971 and Ser. No. 133,007 filed Apr. 12, 1971, and Ser. No. 140,480 filed May 5, 1971. Such a sloping or horizontal casting position offers considerable advantages in comparison with the vertical casting. The metal feeding is easier; no underpressure is necessary. The metal strip is discharged in a more convenient position from the machine and there is no necessity to bend excessively the discharged strip in its hot, brittle condition. The strips can be better watched by the operator and are more accessible.

In the casting machines of this type, there is a danger at the beginning of the casting operation, that the metal melt will flow around the nozzle into the narrow space between the nozzle and the superposed half-molds as soon as a solid starting head is formed on the starter bar. After the start of the machine (the initiation of the circular movement of the half-mold tracks and, simultaneously, of the pulling out of the starter bar) the aforementioned danger practically disappears. Consequently, the machine must be started in an exact time instant. On the other hand, a premature start of the machine may cause that the liquid metal melt pours out of the mold space in the direction of casting. Both the penetration of the melt into the space between the nozzle and the half-molds and the outflow of the melt from the mold space result in an immediate interruption of the casting process.

It has been found as desirable to provide a sufficient room for the creation of the starting head; in other words, the distance between the starter bar and the nozzle outlet must be sufficiently dimensioned. As a result, a rich quantity of metal melt can stream into the mold space prior to the formation of the starting head,

so that a solidification of the melt on and in the nozzle is securely prevented.

The correct dimensioning of the mold space between the nozzle outlet and the starter bar is dependent on the size of the machine, especially on the size of the halfmolds, as well as on the kind of the cast metal, the metal temperature and the like. As for example, the distance between the nozzle outlet and the starter bar (the solidification distance) may amount to 600 mm at the beginning of casting of a 20 mm thick and 1,500 mm wide aluminum strip.

It is,'therefore, an object of this invention to provide means for the prompt starting of the movement of the endless mold tracks at such an instant after the beginning of the casting process as to prevent the metal melt both from penetrating the space between the nozzle and the half-molds and from discharging from the mold space in the direction of casting.

Another object of this invention is to provide such means which can be applied not only for a slightly inclined machine (and thus for a correspondingly inclined united mold) but also for a horizontal or a vertical or an almost vertical casting.

SUMMARY OF THE'INVENTION The above-mentioned objects are attained by a pair ofelectrical contacts arranged in the joint between two consecutive half-molds in such a manner as to be shortcircuited by the incoming metal melt; the short-circuit produces a signal for starting the machine, that is for initiating the circular movement of the endless mold tracks. The start can be accomplished manually or,

' with advantage, automatically.

In the case of a slightly inclined or horizontal casting, thecontact elements are located preferably between two consecutive half-molds of the lower half-mold track, since the short-circuit due to the poured-in metal and consequently the signal occur earlier than the case would be if the contacts were clamped to the upper half-mold track. This time advance of the signal has the advantage that the inertia of the machine is compensated during the start. The contact elements are preferably in the form of insulated wires with free contact tips. As soon as the united half-molds become separated, the contact wires are removed because they are needed at the beginning'of the casting process only.

The contact tips should project only slightly into the mold space. The size of the wire (it can be a flat or a round one) has to be as low as possible in order to avoid disturbances in the minute tolerance between the two adjoining half-molds.

BRIEF DESCRIPTION OF THE DRAWING The invention will now be described in conjunction with the accompanying drawing, in which:

FIG. 1 is a schematic perspective view of a bottom endless half-mold track with the circuit of this invention;

FIG. 2 is a schematic side elevational view of a prior art casting machine having endless mold tracks; and

FIG. 3 is a view similar to FIG. 2 with a circuit for carrying out the starting method of this invention.

DETAILED DESCRIPTION I With reference to the figures, the casting machine has a top caterpillar or endless half-mold track 10 and a bottom caterpillar or endless half-mold track 11. The

circulating motions of respective movable parts are indicated by arrows in FIG. 3. The top half-molds 12 of the top track are periodically put together with the opposite bottom half-molds 13 of the bottom mold track 11. The united half-molds l2 and 13 run for a certain distance 14, predetermined by the design of the machine, in a straight direction and form in these limits, indicated by dashed lines, the actual mold. This mold, in the given example, is composed of two-times seven half-molds. For the reason of simplicity, the illustration of all supporting and fastening components on the supporting frame 15 is omitted. Only in FIG. 1 there are indicated driving teeth segments 16 for bottom half-molds 13. A melt feeding trough 17, a casting nozzle 19, and a stopper 18 are situated at the pour-in site of the mold whereas the starter bar 20 with a guiding rod 21 and the advancing mechanism 22 are located at the discharge end of the mold tracks.

According to this invention, two contact elements 23, such as free tips of an insulated wire, are clamped in the joint between two adjoining half-molds 13; the distance of the joint from the site of pouring has been determined by tests. It has been experimentally found, for example, that the interval of 200 mm from the outlet of the nozzle 19 is an optimum distance provided that the solidification distance is 600 mm and the clearance of the mold space is 20 mm X 1,500 mm. The contact elements 23 are connected through a signal lamp 25 on a control panel 26 to a current source 24. As soon as the front line of the melted metal short-circuits the contacts 23, the signal circuit becomes closed and the signal lamp 25 lights up.

Before the beginning of the casting operation, the

half-molds l2 and 13 are preheated so as to maintain a temperature of about 70 C at the moment of pouring-in of the metal melt, and, thereupon, they are sprayed by a graphite slur. The melted metal in the supply trough 17 is prevented from entering the nozzle 19 by a stopper 18. The melted metal is fed into the supply trough 17 until the metal level exceeds a little (50 mm, for example) the inlet of the nozzle 19. In this manner it is guaranteed that, upon pulling out the stopper 18, a sufficient amount of the metal melt for filling up in a few seconds the nozzle and the mold is for disposal; the melt is supported to flow through the nozzle in a wide front without causing any solidification deposits in the latter.

As soon as the melt stream reaches the contact elements 23 (such as, for example, Duroflex varnished wires of 0.3 mm (1)) arranged at the predetermined distance within the mold space, the current circuit is closed as mentioned above. The light of the signal lamp provides a signal for starting the casting machine. Provided that the casting machine is equipped with a cooling system according to the Swiss Pat. No. 456,056, a blower for producing an underpressure in the mold coolers as well as a cooling water pump (with a little delay) are set into operation simultaneously with the start of the casting machine. Since the casting machine needs a certain amount of time upon its start to get the mold tracks accelerated to the predetermined speed of their circulation, the contact elements 23 have been set relatively far away (400 mm, for instance) from the starter bar 20. The space between the contact elements 23 and the starter bar 20 is filled up by the metal belt in the course of the acceleration period of the mold tracks.

At the moment when the strip itself is grasped by the advancing mechanism 22, an automatic control of the metal melt level in'the supply trough 17 takes over. At the same time, the entire machine can be inclined to a desired sloping position.

Further modifications will also occur to those skilled in the art and all such are considered to fall within the scope and spirit of the invention as defined in the appended claims.

I claim:

1. An electric circuit for use in signalling the instant for starting a casting machine,

a mold formed of opposite groups having movable mold blocks joined in the mold path to complete the mold, and a metal feeding nozzle communicating with the entrance of the mold,

comprising, in combination,

two insulated wires spaced apart from each other and clamped in a joint between two adjacent mold blocks and thereby positioned at a predetermined distance downstream from the nozzle, said wires being sufficiently thin so that said joint will remain narrow enough to restrain metal leakage,

said wires having conductive tips projecting into the mold for being shunted by the leading portion of the poured-in stream of metal; and

signalling means responsive to the shunting of the two wires operable for indicating the instant for starting the casting machine.

2. An electric circuit as claimed in claim 1, said wires having diameter up to 0.3mm.

it I I It 

1. An electric circuit for use in signalling the instant for starting a casting machine, a mold formed of opposite groups having movable mold blocks joined in the mold path to complEte the mold, and a metal feeding nozzle communicating with the entrance of the mold, comprising, in combination, two insulated wires spaced apart from each other and clamped in a joint between two adjacent mold blocks and thereby positioned at a predetermined distance downstream from the nozzle, said wires being sufficiently thin so that said joint will remain narrow enough to restrain metal leakage, said wires having conductive tips projecting into the mold for being shunted by the leading portion of the poured-in stream of metal; and signalling means responsive to the shunting of the two wires operable for indicating the instant for starting the casting machine.
 2. An electric circuit as claimed in claim 1, said wires having diameter up to 0.3mm. 